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NUC126
Aug. 08, 2018
Page
190
of 943
Rev 1.03
NUC12
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Clock Source Select Control Register 2 (CLK_CLKSEL2)
Before clock switching, the related clock sources (pre-select and new-select) must be turned on.
Register
Offset
R/W
Description
Reset Value
CLK_CLKSEL
2
0x1C
R/W
Clock Source Select Control Register 2
0x0002_0008
31
30
29
28
27
26
25
24
Reserved
SPI1SEL
SPI0SEL
23
22
21
20
19
18
17
16
Reserved
RTCSEL
WWDTSEL
15
14
13
12
11
10
9
8
Reserved
7
6
5
4
3
2
1
0
Reserved
CLKOSEL
Reserved
Bits
Description
[31:28]
Reserved
Reserved.
[27:26]
SPI1SEL
SPI1 Clock Source Selection
00 = Clock source from 4~24 MHz external high speed crystal oscillator (HXT) clock.
01 = Clock source from PLL clock.
10 = Clock source from PCLK0.
11 = Clock source from 48 MHz internal high speed RC oscillator (HIRC48) clock.
[25:24]
SPI0SEL
SPI0 Clock Source Selection
00 = Clock source from 4~24 MHz external high speed crystal oscillator (HXT) clock.
01 = Clock source from PLL clock.
10 = Clock source from PCLK0.
11 = Clock source from 48 MHz internal high speed RC oscillator (HIRC48) clock.
[23:19]
Reserved
Reserved.
[18]
RTCSEL
RTC Clock Source Selection
0 = Clock source from 32.768 kHz external low speed crystal oscillator (LXT).
1 = Clock source from 10 kHz internal low speed RC oscillator (LIRC).
[17:16]
WWDTSEL
Window Watchdog Timer Clock Source Selection
10 = Clock source from HCLK/2048 clock.
11 = Clock source from 10 kHz internal low speed RC oscillator (LIRC).
Others = Reserved.
[15:5]
Reserved
Reserved.
[4:2]
CLKOSEL
Clock Divider Clock Source Selection
000 = Clock source from 4~24 MHz external high speed crystal oscillator (HXT) clock.
001 = Clock source from 32.768 kHz external low speed crystal oscillator (LXT) clock.
010 = Clock source from HCLK.